<template>
    <div class="app-container">
        <el-input v-model="filename" placeholder="Please enter the file name (default excel-list)" style="width:350px;" prefix-icon="el-icon-document"></el-input>
        <el-button :loading="downloadLoading" style="margin-bottom:20px" type="primary" icon="el-icon-document" @click="handleDownload">
            Export Selected Items
        </el-button>
        <a href="https://panjiachen.github.io/vue-element-admin-site/feature/component/excel.html" target="_blank" style="margin-left:15px;">
            <el-tag type="info">Documentation</el-tag>
        </a>
        <el-table ref="multipleTable"
                  v-loading="listLoading"
                  :data="list"
                  element-loading-text="拼命加载中"
                  border
                  fit
                  highlight-current-row
                  @selection-change="handleSelectionChange">
            <el-table-column type="selection" align="center" />
            <el-table-column align="center" label="Id" width="95">
                <template slot-scope="scope">
                    {{ scope.$index }}
                </template>
            </el-table-column>
            <el-table-column label="Title">
                <template slot-scope="scope">
                    {{ scope.row.title }}
                </template>
            </el-table-column>
            <el-table-column label="Author" width="110" align="center">
                <template slot-scope="scope">
                    <el-tag>{{ scope.row.author }}</el-tag>
                </template>
            </el-table-column>
            <el-table-column label="Readings" width="115" align="center">
                <template slot-scope="scope">
                    {{ scope.row.pageviews }}
                </template>
            </el-table-column>
            <el-table-column align="center" label="PDate" width="220">
                <template slot-scope="scope">
                    <i class="el-icon-time"></i>
                    <span>{{ scope.row.display_time }}</span>
                </template>
            </el-table-column>
        </el-table>
    </div>
</template>

<script>

    import { fetchList } from '/vue/api/article.js';
    import * as excel from '/vue/vendor/Export2Excel.js';
    module.exports = {
        name: 'SelectExcel',
        data() {
            return {
                list: null,
                listLoading: true,
                multipleSelection: [],
                downloadLoading: false,
                filename: ''
            }
        },
        created() {
              this.fetchData();
        },
        methods: {
            fetchData() {
                this.listLoading = true
                fetchList(this.listQuery).then(response => {
                    this.list = response.data.items
                    this.listLoading = false
                })
            },
            handleSelectionChange(val) {
                this.multipleSelection = val
            },
            handleDownload() {
                if (this.multipleSelection.length) {
                    this.downloadLoading = true
                        const tHeader = ['Id', 'Title', 'Author', 'Readings', 'Date']
                        const filterVal = ['id', 'title', 'author', 'pageviews', 'display_time']
                        const list = this.multipleSelection
                        const data = this.formatJson(filterVal, list)
                        excel.export_json_to_excel({
                            header: tHeader,
                            data,
                            filename: this.filename
                        })
                        this.$refs.multipleTable.clearSelection()
                        this.downloadLoading = false
                } else {
                    this.$message({
                        message: 'Please select at least one item',
                        type: 'warning'
                    })
                }
            },
            formatJson(filterVal, jsonData) {
                return jsonData.map(v => filterVal.map(j => v[j]))
            }
        }
    }
</script>
